Added documentation for expected columns selection input per chart type

README.md

@@ -89,6 +89,13 @@ enum ChartType {
 }
 ```
 
+### Columns selection per chart type
+| Chart type:                                                                                                                | X-axis:            | Y-axis:          | Split-by:          |
+| ------------------------------------------------------------------------------------------------------------------------   | ------------------ | ---------------  | ------------------ |
+| Line / Scatter / UnstackedArea </br> StackedArea / PercentageArea / UnstackedColumn </br> StackedColumn / PercentageColumn | [Single selection]<br/>DateTime / Int / Long </br> Decimal / Real / String | [If split-by column is selected: y-axis restricted to single selection] <br/> [If split-by column is not selected: y-axis can be single/multi selection] <br/> Int / Long / Decimal / Real | [Single selection] <br/> String |
+| Pie /  Donut                                                                                                               | [Single selection]<br/> String | [Single selection]<br/> Int / Long / Decimal / Real | [Single / Multi selection] <br/> String / DateTime / Bool |
+
+
 ### ColumnsSelection
 ```typescript
 interface IColumn {
@@ -103,6 +110,8 @@ class ColumnsSelection {
 }
 ```
 
+See [Columns selection per chart type](#Columns selection per chart type) 
+
 ### AggregationType
 ```typescript
 enum AggregationType {